Lithium niobate (LiNbO3) is one of the most common electro-optic crystals used for active Q-switching of lasers and for optical modulators. Lithium Niobate is well known to have a strong pyroelectric effect that causes charges to be built up on its crystal C-faces when the crystal temperature changes. These charges impose an electric field across the crystal that can cause a significant reduction in effective Q-switch attenuation and the hold-off level, thereby reducing the maximum energy that can be stored in a laser gain medium for light output from the laser.
The effects of pyroelectric charges in niobate are negligible at room temperatures and above because the crystal conductivity is sufficient to allow the surface charge to be dissipated. At low temperatures, however, the conductivity is much smaller, so that the pyroelectric charges remain, causing a large reduction in the Q-switch hold-off. One technique for mitigating this cold temperature problem has been to place a radioactive Americium near the crystal faces to neutralize the surface charges. However, such uses of a radioactive material can be costly, and may entail storage and licensing requirements.